Summary

The create-vault Browse picker no longer filters to *.lbx, so vaults at extensionless paths (the old default name was secret) can be created and reselected like any other file. This was the last picker still carrying an add_filter("LUKSbox vault", &["lbx"]) call - open_existing_picker and the unlock-view Browse handler already dropped their filters with a documented rationale.

Why this matters

#12 has two users (devoid1, Hxs2fJKjYZ) who cannot work with extensionless vaults through the GUI, and you noted you would fix the extension handling. The codebase already documents why no filter variant works cross-platform (the comment block in open_existing_picker: &["lbx"] hides extensionless files, &["*"] becomes a *.* glob on Linux xdg-desktop-portal, &[] is portal-dependent). This change applies that same convention to the one remaining inconsistent site, the create-vault save_file() dialog in crates/luksbox-gui/src/app.rs, with a short comment pointing at the rationale.

Testing

• cargo check -p luksbox-gui --no-default-features passes (hardware/fuse features need macFUSE + libfido2, not available on this machine; the change is GUI-only)
• cargo fmt -p luksbox-gui -- --check clean
• Behavior: the create picker now renders the unfiltered directory listing exactly like the open/unlock pickers; manual path entry is unchanged

Fixes #12